Background: Accurate risk assessment for carcinogens requires an understanding of the link between the presence of the chemical in human tissues and the resulting biological effects of the exposure. Sensitive techniques are needed to measure the phenotypic effects of exposure and for studying genetic changes that may be directly in the pathway of the disease process. In addition, discovery of new genes in environmental response pathways and new polymorphisms in these response pathways has become an important focus. Previously we have developed quantitative methods to detect exposure-induced expression of CYP1A1, CYP1A2, UGT1, PAI2, and TGFa, and the oncogenic translocation in Bcl-2 t(14;18).Aims: Develop technology and capacity for: 1) discovery of genes expressed as a result of exposure, 2) quantitative measurement of exposure-induced expression 3) detection of germline polymorphism 4) Bioinformatic derived genetic markers. Accomplishments: 1) Developed exposure model using lymphoblastoid cell lines and test with cDNA microarray analysis of gene expression Exposure to BPDE was chosen to produce DNA adducts, chromosome aberrations and measurable apoptotic and cell cycle effects.2) Highly sensitive quantitative PCR methods (Taqman) have been developed to monitor CYP1A1 (PAH inducible), CYP1B1, GSTP1, COX2, GADD45, GADD153 (cell cycle arrest/damage inducible) expression and these methods will be used to independently verify inducibility (positive controls).3) Using our recently developed oligo ligation- based ELISA assay (OLA) for NAT1 polymorphisms, we have analyzed ~ 9,000 genotypes. 4) Bioinformatics - A combinatorial genomic methodology for identifying unique markers from whole genomes has been developed and is the subject of an employee invention report.Significance: Development of these biomarker techniques will allow us to test hypotheses concerning the role of environmental and genetic factors in understanding the etiology of human disease. - Biomarkers, PCR, genetics, polymorphism, oligonucleotide ligation assay, OLA, TCDD,